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Given that we are utilizing the methodology from the ITU, I’m inclined to believe it is in our general best interest to align our terminology with that used in specifications such as G.698.2, at least as much as possible within the constraints
of 802.3. In other words, my general inclination would be to diverge only if we need to diverge, and otherwise to align so as to avoid confusion by using the same term to mean different things. With that in mind, I just spent some time re-reading G.698.2 (or at least part of section 5), as well as looking at our definitions in D3.0, and I’d appreciate some help in clarifying something. What stood out for me is that we appear to have diverged on our definition of the term “DWDM Link”. In G.698.2 Figure 5-1, it appears to me as if “black link” and “DWDM link” are roughly equivalent, as they define what lies between S(s)
and R(s) (equivalent to TP2 and TP3 respectively in 802.3ct); the difference, I suppose, is that a “black link” is a form of “DWDM link” that is “black” (or uses the black link methodology to describe it). However, in looking at the definitions in 802.3ct’s
changes to 1.4.237, it appears that “DWDM link” is different: it includes the PHYs, but only includes a single link between those two PHYs. A DWDM system is therefore the aggregate of the DWDM links, or everything including the PHYs (which I presume includes
the transmitter and receiver). Do I have that right? Or am I misunderstanding the definition of a DWDM PHY? I’d appreciate the feedback from experts in helping me to better understand the intent of these terms. Because if I’m right that we’re using those terms differently, I can’t help but wonder if that’s leading to some other points of confusion here… Thanks.
From: John D'Ambrosia <jdambrosia@xxxxxxxxx> Dear .3ct and .3cw Task Forces I want to note to both Task Forces that during the Optical Crosstalk Ad hoc call on 12/21 – the topic of naming the box between TP2 and TP3, which 802.3ct decided to call “black link” came up again. Some individuals disagreed with the decision
of the 802.3ct TF to use the term “black link” to describe the methodology and the box between TP2 and TP3. (See comment #i-1 to IEEE P802.3ct Draft 3.0.) While it was recognized this was the decision of the Task Force, I think it would be fair to say not everyone was in agreement. And with full disclosure, I as an individual, am one of those people. I believe the use of “black link” to
define both the methodology and the aggregate group of DWDM channels or the “box” between TP2 and TP3, is just asking to cause confusion for future readers. As previously discussed in my presentation to the .3ct TF -
https://www.ieee802.org/3/ct/public/tf_interim/20_1214/dambrosia_3ct_01b_201214.pdf, there are also other issues related to both project’s PAR scopes
PHYs are defined as part of DWDM Systems, so there is a certain lack of clarity / conciseness with our PAR scopes, given our definition of DWDM systems and our scope to define physical layer specifications. I still believe the easiest path to success was the 2nd option recommended in the presentation –
Consider redefining “DWDM system” to be what is defined in Clause 154.6 / Fig 154-3. See Slide #7
However, as I noted this approach does not appear in line with the approach defined in G.698.1 and G.698.2. If people don’t find black link acceptable to describe the aggregate of DWDM channels between TP2 and TP3, and don’t like DWDM systems, then we will need to consider another term, such as “DWDM Network” and evaluate potential ramifications
to project documentation. Hopefully – this email will help kick off some additional conversation on the reflector that can lead to consensus building. Regards John D’Ambrosia Chair, IEEE P802.3ct Task Force Chair, IEEE P802.3cw Task Force To unsubscribe from the STDS-802-3-DWDM list, click the following link:
https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-DWDM&A=1 To unsubscribe from the STDS-802-3-DWDM list, click the following link: https://listserv.ieee.org/cgi-bin/wa?SUBED1=STDS-802-3-DWDM&A=1 |